ABSTRACT This exploratory/developmental application proposes to determine the acceptability of a promising new intervention using real-time adherence monitoring and to determine reasons for missed antiretroviral therapy (ART) doses in young AAMSM. Adherence to ART is critical to prevent morbidity, mortality, and emergence of resistant virus. Adherence to Pre-Exposure Prophylaxis (PrEP) with antiretrovirals is critical to prevent HIV transmission. In the US, African American men account for the largest proportion of new HIV infections by race and disproportionately experience associated mortality. Among HIV-positive persons treated with ART, African Americans are significantly less likely than Whites and Hispanics to be virally suppressed. In addition, young MSM have low adherence to PrEP. Guided by the Information Motivation, Behavioral Skills Model, real-time adherence monitoring with a triaged response to missed doses may increase patient information about the consequences of non adherence, motivate medication adherence, and positively influence adherence behavioral skills, resulting in improved behavior that leads to viral suppression and/or more sustained protective PrEP drug levels. The proposed study will recruit young AAMSM from high HIV incidence neighborhoods where improvement in ART adherence has the potential to produce high personal and public health gain, potentially contributing towards lowering HIV incidence rates in these communities. The aims of this study are to: 1) Determine the acceptability of real-time adherence monitoring in young AAMSM by conducting participative formative research with focus groups of young HIV-positive AAMSM patients with detectable viral load in the past 12 months and young AAMSM who are taking PrEP and; 2) Conduct qualitative interviews to determine reasons for missed doses detected in real-time in young HIV-infected AAMSM patients who had a detectable viral load in the past 12 months. We will analyze interview data to identify salient behavioral and/or emergent subpopulation factors that contribute to non adherence. These data will provide a deeper understanding of ART adherence than previous retrospective studies and will inform development of a theory-driven real-time ART adherence intervention including choice of response messages, understanding to what extent perceived social/logistic factors may contribute to these events, and exploring subject's motivation to address reasons for missed doses to prevent future events.